Patent GB-1187693-A (GB)
Title: Sheet or Web Guiding Apparatus
IPC: B65H23/02
Filed: 1968-01-26
Abstract: 1,187,693. Feeding webs. MOUNT HOPE MACHINERY Ltd. 26 Jan., 1968 [16 Feb., 1967], No. 4119/68. Heading B8R. A web-guiding apparatus, which may also be used as a weft straightener, comprises a roll 1 over which the web 2 passes and which is rotatably mounted on a shaft 3, and arms 5, 7 fixed to the shaft ends and to stub shafts 9 mounted in spherical bearings 17, 19. The axis A extending between the bearings 17, 19 intersects the axis B of the roller 1 at its centre, and means are provided for rotating the crank unit comprising parts 3, 5, 7 about the axis A to adjust the inclination of the roll to the travelling web for correcting web deviations. In one embodiment, an arm 21 fixed to the stub shaft 9 is connected at 22 to a piston-rod 24 of an actuator 26 controlled by an edge detector shown as a pivoted finger 31 lightly biased against the edge. Deviation of the web to the right causes the finger 31 to engage a contact L and energize a solenoid 35 for actuating a valve 41 whilst deviation to the left causes a contact R to be engaged to energize solenoids 36, 37 actuating valves 43, 42. The actuator 26 comprises two cylinders 48, 51, the cylinder 48 being connected at one end to the valve 41 and at the other end to atmosphere at 34. The two ends of the cylinder 51 are connected respectively to valves 42, 43. The piston-rod 24 is attached to a piston 50 movable in the cylinder 51 and having an area which is half that of a piston 47 in the cylinder 48. In the neutral position shown with the web centred, pressure is applied to the left hand side of the piston 47 and to the right-hand side of the piston 50. A rod 49 on the piston 49 engages the piston 50 and prevents leftward movement of the piston 50 beyond its central position, the parts being held in this position because of the greater area of piston 50. If deviation of the web to the right causes solenoid 35 to be energized, the valve 41 is actuated to connect the cylinder 48 to exhaust, whereupon both pistons 47, 50 move to the left and actuate the crank unit 3, 5, 7 to apply a corrective action to the web. The connection to exhaust is through a needle valve 39 which can be adjusted to obtain a desired rate of actuation of the crank unit. A relief valve 40 in parallel with the valve 39 is set to exhaust the pressure in the cylinder 48 rapidly until the pressure is approximately half the supply pressure in order that the leftward movement may commence with very slight delay after operation of the valve 41. If the finger 31 is moved to engage contact R, energizing of solenoids 36, 37 causes operation of the valves 43, 42 to exhaust the right-hand end of cylinder 51 and to connect the left-hand end to pressure supply. The piston 50 now moves to the right, causing actuation of the crank unit 3, 5, 7 to apply a corrective action to the web in an opposite sense to that already described. As soon as the finger 31 moves away from a contact L or R, the devices are immediately restored to the neutral position by the pressure on the left-hand side of piston 47, thus preventing hunting. In a modified arrangement (Figs. 7-9), a piston subjected to continuous pressure is connected to the lower end of the arm and biases the crank unit to the neutral position. A second double-acting piston and cylinder is connected to the arm 21 and is operated by valves controlled by the finger 31 so as to move the arm in one direction or the other to effect the correction of the web path. To avoid differential tension effects on the two edges of the web caused by the movement of the roller 1, two rollers (Fig. 10) may be employed, the web passing over one and under the other. The rollers are carried by crank units as described above, the units being connected to move in unison and are operated by a piston and cylinder arrangement such as 26, Fig. 4. The apparatus may be used for weft straightening if the web is arranged to run in a substantially vertical direction over the roller 1 instead of in a substantially horizontal direction as shown in Fig. 1.